


Monster in the Bed

by Julian_McQueen



Category: Undertale (Video Game)
Genre: Frottage, Groping, M/M, Non-Binary Frisk, Other, Sexual Experimentation, Step-Sibling Incest, They are at least 17+
Language: English
Status: Completed
Published: 2015-11-01
Updated: 2015-11-01
Packaged: 2018-04-29 11:26:39
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,440
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5125718
Author URL: https://archiveofourown.org/users/Julian_McQueen/pseuds/Julian_McQueen
Summary: <blockquote class="userstuff">
              <p>Frisk and Asriel like to talk and play during the night, and sometimes things get... "frisky".</p>
            </blockquote>





	Monster in the Bed

Frisk was lying alone in their bed that night, but they were far from tired.

 

It had been a few years since he managed to bring Asriel back, and for a while, things seemed fine. But then Asriel started to have nightmares.

 

It was surprising, but not unexpected, considering what he had been through. There were nights where Frisk would hear Asriel in the other room, crying for hours either for help or to say he was sorry. They would hear Toriel comfort and console him until he work up, and then Asriel would immediately get up, and go to Frisk's room. Frisk wouldn't even hesitate to allow Asriel to snuggle with them, the human being the only thing that ensured a peaceful night's sleep for the goatboy. It was after Toriel realized this that she allowed Asriel and Frisk to share the same bed, and from that night on, Asriel no longer had any nightmares.

 

However, they ended up discovering better ways to stay up during the night, as normal children did. They talked, playing out scenarios of stories the two of them concocted, or talking about events that happened during the day. They discussed school, the differences between humans and monsters, and what their friends did throughout the day. They were innocent, playful discussions at first, but as they got older, their conversations got heavier.

 

It was only natural for the growing teens to be interested in sex as they reached puberty, it was necessary for them to grow and develop. So as a consequence, the nightly discussions between the teens would transition quickly from tales of childish fantasy to the discussion of sex, the stories and adventures they made at nights would quickly turn sexual as their young hormones got hold of them. But the icing on this hormonal cake was that, again unsurprisingly, the nightly conversations would always conclude with faint groans and gasps as Asriel and Frisk would relieve their sexual frustration only inches away from each other.

 

They tried to respect each other's privacy after the first couple of nights. But of course, they both would eventually get... curious.

 

And that was when they ended up discovered even better ways to stay up during the night.

 

Frisk watched as Asriel walked into the bedroom, having finished brushing his teeth and kissing his mother goodnight. Asriel smiled to Frisk as he crawled into the bed, quickly slipping under the covers. Toriel insisted that the boys wore pajamas while they slept, but as they grew older, boxers and t-shirts became more in-fashion.

 

Asriel stretched slightly as he got comfortable, turning to Frisk and grinning. The human grinned back, and the nightly discussion was in-session. Asriel found it to be almost therapeutic at points, he trusted Frisk enough that he told them much about his nightmares, things he didn't even tell Toriel, his own mother. Frisk would respond the same each time he disclosed another horrid anecdote from his twisted past. Asriel would occasionally hesitate, apprehensive that the things he told Frisk were too harrowing for him. But Frisk would always respond the same. A boop to the snootle, a tight hug, and the reassurance that he wasn't Flowey anymore, and he'd never be alone again.

 

Asriel thanked Frisk, and the two would divert their conversation to one of playfulness and creativity. In their latest adventure, Asriel at one point literally stood up in his bed and pretended to be "Albus Corde - The White Warlock of the Fold", while Frisk pretended to be his rival, "The Pirate King Anor Darzi". The two "fought" with pillows, giggling and clamoring until they heard Toriel shout for them to be quiet and go to sleep. They boys giggled and quickly slipped back under the covers, continuing their story.

 

Finally, the two boys talked about sex. It was always the last thing they spoke of, and it was often based on the conversations they heard in school, of how the older boys boasting of their recent endeavors with girls, and how they talked about what they did in great detail. Frisk repeated in detail what the older boy from today did with his girlfriend, the human's face turning hot as he looked at Asriel, trying to see his expression in the darkness. The goatboy was staring at the ceiling, his mind already thinking of such lewd things, and both of them knew what was going to happen next. Frisk and Asriel ended the conversation with a goodnight as the room suddenly grew silent.

 

Asriel flinched slightly as he felt Frisk's arm brush past his, and felt a finger poke into the elastic strap of his boxer shorts. He took a slight breath as he slightly adjusted his hips, which was his signal to go ahead, and felt as Frisk's hand pushed past the elastic strap and into his boxers.

Frisk heard a faint gasp from Asriel as they touched their brother. He felt the goatboy's erection, hot and hard in his hand, and lied there for a few moments. Asriel kept his arms at his sides as he felt Frisk lightly squeeze his erection, faint ebbs of pleasure echoed out of Asriel’s body and his hips pushed slightly in response.

 

Frisk couldn’t help to smile and leaned into Asriel's ear, repeating again the naughty things the older boy did to his girlfriend, and how he played with her like Frisk was playing with Asriel now. Asriel's ear twitched as Frisk continued to whisper lewd things to him, and he pushed into Frisk's grip in response. His breath became shallow as Frisk continued to squeeze his cock, and he shuddered as the human's thumb rubbed his foreskin against his tip.

 

But of course, it wouldn't be fair if Asriel didn't return the favor, and so Asriel heard Frisk give out a satisfied grunt as Asriel reached under Frisk's boxers and grasped their hardened member, feeling pre smear on his palm as he began gently stroking it.

 

The teens lied in the darkness, with only the sound of their hearts pounding as they fondled each other, reveling in the secret pleasure they both shared. It had felt like yesterday when Frisk first suggested it, but now they lost count of how many nights they spent exploring each other’s bodies. Toriel had no idea, and her room was far enough that she couldn't hear anything as long as they were quiet.

 

Things had escalated now. Frisk and Asriel had turned towards each other, their bodies still hidden under the covers. The both had pulled both their boxers down, and were facing each other, their members pressed against each other. Frisk could smell the mint off of Asriel's breath as they grasped their cocks in a tightening grip. They began to slowly jerk both of the members as Asriel pushed his face into Frisk's chest, the human's shirt quickly warming up from the monster's breath. Asriel feet pushed against Frisk's as he pushed his hips closer, wanting to feel his cock pressed harder against his sibling's.

 

The room was significantly hotter now, and the faint sound of the sibling's desperate breaths and grunts could be heard as Frisk continued to jerk the two of them off. They whispered if Asriel wanted him to go faster, and the goatboy nodded as Frisk did such. The monster's fingers dug in Frisk's arm as he started to feel his climax approaching, Frisk quickly responding that they were feeling it too, the only sign of their wavering stamina coming from the cracks in their hushed voice. Asriel placed his hand around Frisk's and helped them pump their cocks, now engorged and twitching as their orgasms were imminent and approaching, as Frisk placed their free hand around the tips.

 

Asriel came first, as usual. The goatboy muttered Frisk's name before he let out a gasp that cut through the silence of the room like a knife. His cock spasmed and spilled seed into Frisk's hand. He was soon followed by Frisk, who also began spilling his load, their cock echoed to Asriel's orgasmic throbs almost to the rhythm of a heartbeat. The two of them shuddered in silence as their orgasms waned, and they felt as their slowly stopped throbbing and began to turn soft. Frisk then got up, and pulled up their boxers before they walked into the bathroom and quickly deposed of Asriel's and their seed in the toilet before heading back.

 

There, the two teens ended up together, cuddling together in the bliss of a united afterglow. Asriel rested his head of Frisk's chest as the two of them drifted into another night of blissful sleep.

 

"Goodnight."


End file.
